Assessment of genetic and epigenetic changes during cell culture ageing and relations with somaclonal variation in Coffea arabica

Long-term cell cultures were used in coffee to study the cytological, genetic and epigenetic changes occurring during cell culture ageing. The objective was to identify the mechanisms associated with somaclonal variation (SV). Three embryogenic cell lines were established in Coffea arabica (2n = 4x = 44) and somatic seedlings were regenerated after 4, 11 and 27 months. Phenotyping and AFLP, MSAP, SSAP molecular markers were performed on 199 and 124 plants, respectively. SV were only observed from the 11 and 27-month-old cultures, affecting 30 and 94 % of regenerated plants, respectively. Chromosome counts performed on 15 plants showed that normal plants systematically displayed normal chromosome numbers and that, conversely, aneuploidy (monosomy) was systematically found in variants. The allopolyploid structure of C. arabica allowed aneuploid cells to survive and regenerate viable plants. No polymorphic fragments were observed between the AFLP and SSAP electrophoretic profiles of mother plants and those of the in vitro progeny. Methylation polymorphism was low and ranged between 0.087 and 0.149 % irrespective of the culture age. The number of methylation changes per plant-normal or variant-was limited and ranged from 0 (55-80 % of the plants) to 4. The three cell lines showed similar SV rate increases during cell culture ageing and produced plants with similar molecular patterns indicating a non random process. The results showed that cell culture ageing is highly mutagenic in coffee and chromosomal rearrangements are directly linked to SV. Conversely, the analysis of methylation and transposable elements changes did not reveal any relation between the epigenetic patterns and SV

Coffee (Coffea arabica L.)

Coffee (Coffea sp .) is a perennial plant widely cultivated in many tropical countries. It is a cash crop for millions of small farmers in these areas. As for other tree species, coffee has long breeding cycles, which makes conventional breeding programs time-consuming. For that matter, genetic transformation can be an effective way to introduce a desired trait in elite varieties or for functional genomics. In this chapter, we describe two highly efficient and reliable Agrobacterium -mediated transformation techniques developed for the C. arabica cultivated species: (1) A. tumefaciens to study and introduce genes conferring resistance/tolerance to biotic (coffee leaf rust, insects) and abiotic stress (drought, heat, seed desiccation) in fully transformed plants and (2) A. rhizogenes to study candidate gene expression for nematode resistance in transformed roots. (Résumé d'auteur

Is American Bureaucracy an Immobilized Gulliver or a Regenerative Phoenix?: Reconsidering the Alleged Demise of Federal Bureaucratic Power

Over the past quarter century, federal bureaucracies have been affected by numerous changes-many of which were designed to restrictbureaucratic autonomy. Several scholars have concluded that bureaucracy's role in the process of governance has been substantially diminished. When the changes are closely inspected, however, most-including the proliferation of political appointees-prove not to be as effective at restraining bureaucracy as often supposed Also, because many restrictions interact with others, they are not really summative; sometimes they cancel each other out.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline